Torsional damper for locking clutch pertaining to a hydrokinetic coupling apparatus, in particular for motor vehicle

ABSTRACT

The invention concerns a torsional damper ( 23 ) comprising an input element and an output element coaxial and movable in rotation relative to each other counter at least to an compression spring ( 300 ), wherein the two adjacent transverse parts, with radial orientation, associated with the input and output elements each comprise a housing ( 306-308, 302 ) receiving the spring ( 300 ) whereof the opposite ends are capable of co-operating with the supporting end surfaces ( 316-318, 304 ) which define the two housings to operate between the two elements; the length (LF) of each of the two associated housings ( 306-308, 302 ), separating the opposite supporting end surfaces, being greater than the length (LR) of the spring ( 300 ) at rest.

The present invention relates to a torsion damper.

In particular, the invention relates to a torsion damper for a lock-upclutch which is adapted to work between the driving element and thedriven element of a hydrokinetic coupling apparatus, especially for amotor vehicle.

In accordance with a known design, the torsion damper comprises an inputelement and an output element which are coaxial with each other androtatable with respect to each other against the action of at least onecompression spring.

The spring or springs are generally of the circumferentially actingtype, being for example arranged substantially on a common diameter.

More precisely, the damper comprises two adjacent, radially oriented,transverse parts which are associated with the two elements, namely theinput element and the output element respectively, and each of whichincludes a housing that receives the spring, the opposed ends of whichare arranged to cooperate with the end abutment surfaces bounding thetwo housings for acting between the two elements.

Regardless of the type of arrangement used for the springs, it may benecessary to provide an angular course of dead travel CM between theinput and output elements before the springs start to operate.

For this purpose, and in accordance with one known design which isindicated diagrammatically in FIG. 6A, one of the two housings, whichare generally configured in the form of windows having contourssubstantially complementary with that of the spring, which is forexample a coil-type compression spring, have a length which issubstantially equal to that of the spring, while the other one has awindow length LF which is generally greater than the length LR of thespring, whereby to make available, with reference to a rest position inwhich the spring is centred in the larger of the windows, a course ofdead travel CM in each of the two directions of rotation, which is equalto one half of the difference in length LF-LR.

It is important, especially for good absorption of vibrations, to beable to provide a course of dead travel of substantial length, moreparticularly when the springs are springs of the so-called “secondorder” type, that is to say in the case where they are part of a secondset of springs which act over a second period after a first set ofsprings of the so-called “first order” type has already actedcircumferentially between the input and output elements.

In this connection, the second order springs are in some arrangementsdisposed radially inwardly, and the space available for mounting thesprings, and more particularly for forming the windows that constitutethe housings which receive them, is reduced.

It is therefore desirable, for example in the case where the springs arearranged circumferentially in a series along a common diameter, to beable to provide the greatest possible number of springs with thegreatest possible angular course of dead travel, while having goodmechanical strength.

With this in view, the invention proposes a torsion damper of the typementioned above, characterised in that the length of each of the twoassociated housings, separating the opposed end abutment surfaces of thehousing, is greater than the length of the spring at rest.

Thanks to this design, and for example in the case where the lengths ofthe two associated housings are equal—for the same spring length LR—thesame course of dead travel CM is available, in both directions ofrotation, as in the solution according to the state of the art withwindows the length LF of which is reduced by a course of dead travel CM.

Thus, for the same desired course of dead travel, it is possible toprovide more springs or, for the same number of springs, the componentsin which the windows constituting the housings are formed are more rigidbecause there is more material present between two consecutive windows.

The two adjacent portions of the inlet and outlet elements, in which thehousings are formed, generally consist of two radially oriented,transverse and substantially flat portions.

Where the springs are second order springs arranged circumferentially ona diameter, each housing is preferably a window formed in thecorresponding flat portion of the element, and the end abutment surfacesconsist of the opposed terminal lateral edges of the window.

The spring is preferably a coil type compression spring.

The two adjacent parts may be, respectively, part of the input elementand output element, the housings being circumferentially orientedhousings which receive a circumferentially acting spring.

In this last mentioned case, the damper includes a set ofcircumferentially acting springs arranged substantially on a commondiameter, and each of which is received in two associated housingsaccording to the invention.

The input element comprises at least one guide ring which retains thecircumferentially acting springs in position radially and which iscoupled to the driven element of the lock-up clutch, and the outputelement comprises a radial plate or web which is coupled in rotation tothe driving element of the lock-up clutch.

The input element may comprise two complementary guide rings, each ofwhich includes a radially oriented transverse portion, the two saidportions being arranged symmetrically on either side of a correspondingradially oriented transverse portion of the radial plate, the said twoguide ring portions including facing windows which, being associated inpairs, constitute a housing of the input element which receives acircumferentially acting spring, which is itself received in a housingof the portion of the radial plate that extends between the two rings.

The two complementary rings include means for coupling them together inrotation, and the circumferentially acting springs, referred to assecond order springs, are arranged on a diameter which is substantiallysmaller than the diameter on which the means coupling the two ringstogether in rotation are located.

Further features and advantages of the invention will appear on areading of the following detailed description, for an understanding ofwhich, reference will be made to the attached drawings, in which:

FIG. 1 is an exploded perspective view, shown partly cut away, of themain components of a hydrokinetic coupling apparatus including a torsiondamper in accordance with the features of the invention;

FIG. 2 is a view in axial elevation in the direction of the arrow F2 inFIG. 1, with one of the guide rings shown partly cut away;

FIG. 3 is a view in cross section taken on the line 3—3 in FIG. 2;

FIG. 4 is a scrap view on a larger scale, which shows the contour andthe form of one of the windows for a second order spring in one or otherof the two associated rings;

FIG. 5 is a scrap view in cross section taker on the line 5—5 in FIG. 4;and

FIGS. 6A and 6B are two diagrams which, in FIG. 6B, illustrate theadvantages that result from the design in accordance with the inventionas compared with the state of the art which is shown in FIG. 6A.

In one design, which is known for example from the documentWO-A-94/07058 (U.S. Pat. No. 4,590,750), to which reference can be madefor more detail, a hydrokinetic coupling apparatus includes, arranged ina common sealed housing filled with oil and constituting a casing, atorque converter and a lock-up clutch 1.

The casing, which in this example is of metal, constitutes a drivingelement and it is arranged to be coupled in rotation to a driving shaft,for example a crankshaft of an internal combustion engine (not shown) inthe case of application to a motor vehicle.

The casing, which is of generally annular form, consists of two halfshells which are arranged facing towards each other and which are fixedin a sealed manner at their outer periphery, usually by a weldingoperation.

The first shell 2, 3 is arranged to be coupled in rotation to thedriving shaft, and it consists essentially of an annular wall 2 which isoriented generally transversely, that is to say it lies in a radialplane at right angles to the axis X—X of the apparatus, and it isextended at its outer periphery by a generally axially oriented annularcylindrical wall 3.

The second shell (not shown in the drawings in the interests ofsimplicity, the same being true for the reaction wheel of the converter)is so configured as to define an impulse wheel with vanes projectingfrom the inner face of that half shell. These vanes lie facing towardsthe vanes of the turbine wheel 4 which is secured by riveting or weldingto a hub plate 102 coupled in rotation with a hub 5, which is splinedinternally for coupling it in rotation to a driven shaft (not shown),which may for example be the input shaft of the gearbox in the case ofapplication to a motor vehicle.

The driven shaft is hollow so as to define an internal duct thatprovides access for oil to a guide sleeve 6, which in this example issolid and which is fitted axially between the hub 5 and the transversewall 2. The guide sleeve consists of a front portion 106 which acts as acentring device, and a rear portion 108. The portion of the guide sleeve6 having the smaller diameter is the front portion 106, the function ofwhich is to provide fastening of the guide sleeve 6 to the transversewall 2, in this example by welding, while the rear portion 108, havingthe larger diameter, is bounded radially on the outside by a machinedcylindrical surface 110 for the axial sliding guidance of a piston 9,which has for this purpose a central, axially oriented sleeve portion112 which in this example is directed axially towards the rear, that isto say towards the plate 102 of the splined hub 5.

The surface 110 includes a groove which receives an annular sealing ring(not given a reference numeral) for sealing the sliding movement of thesleeve portion 112 along the surface 110. The hub 5 has a front portionwhich penetrates into the interior of the sleeve 6.

In accordance with a known design, the piston 9 defines, with the guidesleeve 6, the transverse wall 2 and an annular disc 10 (which carriesfriction liners 11, secured for example by adhesive bonding on each ofits transverse opposed faces) defines a variable volume chamber 30 whichis fed through the guide sleeve 6, which has holes for this purpose (notgiven a reference numeral).

The disc 10 is fitted at the outer periphery of the piston 9, and at itsouter periphery, radially beyond the piston 9, it has lugs with aradially oriented portion 200 formed with notches 202, into each ofwhich there penetrates an axially oriented drive lug 14 formed in theouter part of an external guide ring 12.

The disc 10 is carried by the ring 12, and is thereby coupled inrotation to the guide ring 12, but with axial movement being possible,by means of a coupling 13 of the tenon and mortice type comprising thelugs 14 and notches 202.

The lugs 14 are oriented axially, and are formed by stamping and bendingso as to project from the generally transversely oriented portion 206 ofthe external guide ring 12, which in this example is a metal ring.

The lugs 14 extend axially towards the internal face 124 of thetransverse wall 2.

The transverse portion 206 is extended at its outer periphery by anaxially oriented annular portion 15 in the form of an annularcylindrical skirt, which serves to hold in position, radially on theoutside, coil springs 16 which are also held radially on the inside byan annular retaining portion 17 of an internal guide ring 18.

The internal guide ring 18 has an internal transverse portion 208 in theform of a flat annulus, which is joined to the annular portion 17, ofgenerally frusto-conical form, for retaining the springs 16, and whichis itself extended externally by a transverse second portion 201 in theform of a flat annulus, which is parallel to the first transverseportion 208 and which is offset axially with respect to the lattertowards the turbine wheel 4.

The transverse second portion 201 of the ring 18 has at its outerperiphery notches 212, which in the embodiment shown in detail in FIGS.2 and 5 consist of slots into which there penetrate axially-orientedshouldered tenons 211, which are formed at the free end of the annularportion 15 of the external guide ring 12 adjacent to the piston 9.

In a known way, by upsetting, in a seaming operation, the ends 216 ofthe tenons 211 in contact with the face of this second transverseportion 201 of the internal guide ring 18 facing towards the turbinewheel 4, a seamed connection of the tenon and mortice type is formedbetween the two guide rings, namely the external guide ring 12 and theinternal guide ring 18.

The tenons 211 are formed in the free terminal edge of the annularportion 15, and they extend axially in the opposite direction from thedrive lugs 14 which are offset internally towards the inside withrespect to the said portion 15, which is disposed as close as possibleto the wall 3 of the half shell, so as to locate the springs 16 moretowards the outside, thereby improving performance.

The tenons 211 have a central recess for the purpose, in a known way, offacilitating flow of the material in contact with the face of the secondportion 201 during the seaming operation.

The internal guide ring 12 is therefore robust. It will be noted thatthe lugs of the disc 10 are offset axially towards the turbine wheel 4with respect to the main portion of the disc 10 carrying the frictionliners 11, so as to decrease the length of the lugs 14, reduce axialsize, and avoid any interferences.

The guide rings 12 and 18 are secured together at their inner peripheryby means of short boss members 24.

The rings 12 and 18 are disposed axially on either side of a radialplate 19, which is provided with circumferential apertures 25, throughwhich the boss members 24 extend with a circumferential clearance.

For this purpose, the external guide ring 12 has a transversely orientedannular portion 222 which is adjacent to the transverse surface 224 ofthe radial plate 19 and in facing relationship with it, while thetransverse first portion 208 of the radially oriented internal guidering 18 is adjacent to the surface 226 of the disc 18 adjacent to theturbine 4.

At its outer periphery the radial plate 19 has radial lugs 20 whichdefine engagement portions for the circumferential ends of thecircumferentially acting springs 16.

The lugs 20 (FIG. 1) carry circumferential fingers for holding thecoil-type springs 16, with the said fingers penetrating into theinterior of the springs 16 that extend between two lugs 20.

The internal guide ring 12 and the external guide ring 18 are providedwith mutually facing press-formed elements 230 and 232 respectively, forengagement with the circumferential ends of the springs 16, the lugs 20being able to penetrate between the press-formed elements, which stiffenthe rings 12, 18.

Thus, thanks to the first set of circumferentially acting coil springs16, which are referred to as first order springs, the disc 10 iselastically coupled to the radial plate 19 to give good absorption ofvibrations.

The radial plate 19 is secured by riveting, or by welding in anotherversion, to the hub plate 102 of the splined hub 5, at the same time asthe turbine wheel 4 which for this purpose has lugs (not shown) at itsouter periphery. The radial plate 19 is secured by means of its internalradial portion, in the form of a flat annulus 80 which lies insubstantially the same plane as the lugs 20 and which is offset axiallytowards the turbine wheel 4 with respect to the outer radial portion, inthe form of a flat annulus 82, through which the boss members 24 extend.

With the exception of the seals and the friction liners 11, thecomponents of the hydrokinetic coupling apparatus are of metal, beingtypically in the form of steel pressings apart from the springs 16.

Thus, the lock-up clutch 1 includes a torsion damper 23 which is fitted,in the axial sense, mainly between the turbine wheel 4 and the wall 2 atthe outer periphery of the first shell 2, 3, with an input partconsisting of the ring 12 disposed radially outwards of the piston 9 andfriction liners 11, the damper consisting of the guide ring 12 in theform of a half shell, the coil springs 16, and an output part consistingof the radial plate 19.

The output part 19 is coupled in rotation to the turbine wheel 4, andmore precisely to the splined hub 5 of the latter, while the input part12 is coupled in rotation to the disc 10 which projects radially withrespect to the piston 9. The input part 12 is thus coupleddisengageably, via the disc 10 and the liners 11, to the driving shaft.The disc 10 with its friction liners 11 is arranged to be grippedaxially and disengageably on the piston 9 and the facing portion of theinner surface 124 of the transverse wall 2, which constitutes acounter-piston. The disc 10 is thus coupled elastically to the splinedhub 5 and to the turbine wheel 4.

It will be noted that the piston 9 is coupled in rotation to thetransverse wall 2 of the first shell by means of tangentially orientedresilient tongues 40 which are spaced apart at regular circumferentialintervals, and these tongues 40 enable the piston 9 to move axially.

For attaching the tongues to the piston 9, two-part fastening means areused such as to necessitate working on only one side of the piston 9, asis described in the document FR-A-2 726 620, to which reference can bemade.

In the event of relative rotation between the input part consisting ofthe ring 12 and the output part consisting of the plate 19, thecircumferentially acting springs 16 are compressed, so as to permit thisrelative displacement to take place.

It will be recalled that by causing a variation to take place in thepressure within the chamber 30 fed through the sleeve and the drivenshaft, the liners 11 can be gripped in such a way as to avoid, after thevehicle has been started, any sliding movements between the turbine andimpulse wheels.

In one known design, the torsion damper 23 includes a second set ofcircumferentially acting springs 300, or so-called second order springs.

The springs 300, of which there are eight in this example, are coil-typecompression springs, all of which are disposed circumferentially on thesame diameter, this diameter being smaller than the diameter on whichthe boss members 24 are fitted, that is to say the second order springs300 are located generally radially inwardly with respect to the firstorder springs 16.

For this purpose, each spring 300 is received in a housing 302 in theform of a window which is formed in a central portion 304, in the formof a flat annulus, of the radial plate 19 which lies in a plane that isoffset axially, towards the internal face 124 of the transverse wall 2,with respect to the plane of the lugs 20 and the inner radial portion 80of the radial plate 19.

The circumferential length of each window 302 is bounded by theseradially oriented, opposed lateral terminal edges 304.

As can be seen in particular in FIG. 2, the circumferential length ofthe window 302 is generally greater than the circumferential length ofthe corresponding spring 300.

In order to receive each spring 300 which extends axially on either sideof the radial plate 19 out of its window 302, the associated outer guidering 12 and inner guide ring 18 include pairs of associated windows 306and 308. To this end, the external guide ring 12 and internal guide ring18 each have a transverse inner portion in the form of a radiallyoriented flat annulus, 310, 312 respectively.

These flat portions 310 and 312 are parallel and adjacent to the radialplate, lying in facing relationship with the portion 303 of the radialplate 19 that includes the windows.

As can be seen in FIGS. 4 and 5, for example in the case of the externalring 12, the windows 306 are formed by stamping out and press-forming inthe portion 310, and they are configured with curved longitudinal edges314 so as to conform with the cylindrical outer profiles of the coilsprings 300 which they receive.

The windows 306 and 308 thus have a robust contour which enables thesprings 300 to be properly retained.

The circumferential length of each window 306, 308 is bounded by therespective opposed terminal lateral edges 316, 318 of the window.

The rings 12 and 18 are associated with each other through the bossmembers 24, each of which extends through an oblong passage 25 in theradial plate 19, so that the associated windows 306 and 308 are infacing relationship with each other, the windows 306 and 308 havingcircumferential lengths LF which are equal to each other, and also, inthe embodiment of the invention shown in the drawings, a length which isequal to the circumferential length of the corresponding window 302 ofthe radial plate 19.

The advantage obtained by the design according to the invention will nowbe explained with reference to FIGS. 6A and 6B.

In the design according to the prior art which is shown diagrammaticallyin FIG. 6A, the circumferential length of the windows 302 of the radialplate 19 is substantially equal to the length LR of the spring 300 atrest, while the windows 306 and 308 of the rings 12 and 18 have a windowlength LF which is generally greater than the length LR, so that acourse of dead travel CM is obtained in both directions when, startingin the rest position shown in FIG. 6A, the input element consisting ofthe rings 12 and 18 is able to be displaced angularly in one directionor the other with respect to the output element consisting of the radialplate 19, through an angular course of travel corresponding to thecircumferential dead travel CM, this taking place before the secondorder springs start to operate.

Thanks to the design according to the invention which is showndiagrammatically in FIG. 6B, the length of the windows 302 in the radialplate 19, and the windows 306 and 308 in the rings 12 and 18, aresubstantially equal to each other and have a common length LF which isgreater than the length LR of the spring 300.

It is found that a circumferential dead travel CM in each direction isobtained which is equal to that in the version of the state of the artin FIG. 6A, by making windows 306, 308 such teat their length LF isreduced by a dead travel CM as compared with the state of the art. Thus,in order to obtain a common dead travel CM in both directions, it isenough to make the windows 302, 306, 308 such that their length is equalto LR+CM, whereas the solution according to the state of the art made itnecessary to give the windows 306, 308 a length LF equal to LR+2CM.

It will be noted that the whole contour of the windows 306, 308 iscurved.

In another version, the torsion damper may consist of a friction clutch,the radial plate 19 being fixed to a hub which is splined internally sothat it can be coupled in rotation with the input shaft of the gearbox,in the case of application to a motor vehicle.

A support disc, carrying a friction liner secured on each of its faces,is then secured by riveting to the guide ring 12, which then has nodrive lugs.

The liners are arranged to be gripped between the pressure and reactionplates of the clutch, which are rotatable in that case with thecrankshaft of the engine of the vehicle. For more detail, referenceshould for example be made to the document EP-A-0 286 213 (U.S. Pat. No.5,004,088).

What is claimed is:
 1. A torsion damper (23) comprising an input element(12, 18) and an output element (19) coaxial with each other androtatable with respect to each other against the action of at least onecompression spring (300), in which each of two adjacent, radiallyoriented, transverse parts (310-312, 303), associated with the twoelements that comprise the input element (12, 18) and output element(19), includes a housing (306-308, 302) that receives the spring (300),the opposed ends of which are arranged to cooperate with end abutmentsurfaces (316-318, 304) that bound the two housings so as to act betweenthe two elements, characterised in that the length (LF) of each of thetwo associated housings (306-308, 302), separating the opposed endabutment surfaces of the housing, is greater than the length (LR) of thespring (300) at rest.
 2. A torsion damper according to claim 1,characterised in that the lengths (LR) of the two housings (306-308,302) associated with each other are equal.
 3. A torsion damper accordingto claim 1, characterised in that the two adjacent parts (310-312, 303)are two radially oriented, transverse, substantially flat parts, in thateach housing (306-308, 302) is a window formed in the corresponding flatportion of the element, and in that the said end abutment surfaces(316-318, 304) consist of the opposed terminal lateral edges of thewindow.
 4. A torsion damper according to claim 1, characterised in thatthe spring (300) is a coil type compression spring.
 5. A torsion damperaccording to claim 1, characterised in that the said two adjacent partsare respectively part of the input element (12, 18) and output element(19), and in that the housings are circumferentially oriented housingswhich receive a circumferentially acting spring.
 6. A torsion damperaccording to claim 5, characterised in that it includes a set ofcircumferentially acting springs (300) arranged substantially on acommon diameter, and each of which is received in said two associatedhousings (302, 306-308).
 7. A torsion damper according to claim 6,characterised in that the input element comprises at least one guidering (12, 18) which retains the circumferentially acting springs (300)in position radially and which is coupled to the driven element of alock-up clutch, and in that the output element comprises a radial plate(19) which is coupled in rotation to the driving element of the lock-upclutch.
 8. A torsion damper claim 7, characterised in that the inputelement comprises two complementary guide rings (12, 18), each of whichincludes a radially oriented transverse portion (310, 312), in that thetwo said portions are arranged symmetrically on either side of acorresponding radially oriented transverse portion (303) of the radialplate (19), and in that the said two portions of the guide rings includefacing windows (306, 308) which, being associated in pairs, constitute ahousing of the input element (12, 18) which receives a circumferentiallyacting spring (300), which is itself received in a housing (302) of theportion (303) of the radial plate (19) that extends between the tworings.
 9. A torsion damper claim 8, characterised in that the twocomplementary rings (12, 18) include means (24) for coupling themtogether in rotation, and in that the circumferentially acting springs(300) are arranged on a diameter which is substantially smaller than thediameter on which the means (24) coupling the two rings together inrotation are located.
 10. A torsion damper according to claim 6,characterised in that the torsion damper acts between the drivingelement and the driven element of a hydro-kinetic coupling apparatus.